Duplex cable telegraphy.



I. KITSEE. DUPLEX CABLE TELBGRAPHY.

APPLICATION FILED MAY 20, 1908. RENEWED APR. 29, 1909.

942,208. Patented Dec. 7, 1909.

ISIDOR KI'ISEE, OF PHTLADELPHIA, PENNSYLVANIA.

DUPLEX CABLE TELEGRAPHY.

Specification of Letters Patent.

Patented Dec. '7, 1909.

Application filed. May 20, 1908, Serial No. 433,806. Renewed April 29,1909. Serial No. 492,991.

To all whom it may concern:

Be it known that I, Ismon Krrsnn, a citizen of the United States,residing in the city of Philadelphia, county of Philadelphia, and Stateof Pennsylvania, have invented certain new and useful Improvements inDuplex Cable Telegraphy, of which the follow ing is a specification.

My invention relates to electric telegraphy and more particularly toduplex telegraphy over long lines or circuits, such as long land lines,submarine, subterranean, or aerial cables, or, in fact, any circuit orconductor, especially when having great capacity.

My invention resides in a duplex telegraph system, particularly for useover lines or circuits of the character above described, in whichimpulses alternating in polarity are impressed upon the line and thereception of signals effected by means of a transformer in whosesecondary circuit is connected the receiving apparatus, there being athird coil on the transformer, or associated therewith, for renderingthe receiving apparatus at a given station unresponsive to impulsestransmitted from that station. And it is characteristic of my system ofduplex telegraphy for use on lines or circuits of the kind describedthat there is no artificial line employed.

My invention resides also in other features hereinafter described andclaimed.

For an illustration of one of the forms my invention may take, referenceis to be had to the accompanying drawing, in which:

Figure 1 is a diagrammatic view of the circuits and apparatus at twostations adapted to communicate with each other. Fig. 2 is a view of oneof the forms of transformer that may be employed.

Referring to Fig. 1, L represents a line conductor, which may be that ofa land line, a submarine, an aerial, or a subterranean cable, or, infact, any conductor, especially when of such length or so disposed thatit has relatively great capacity. This conductor L joins two stations,the apparatus at both being similar.

Connected in the line are opposed sources of energy B and B connected inopposition to each other, and one of greater electro-motive force thanthe other, the line circuit extending through these sources to the earthE, or any suitable return conductor. Connected in shunt to one of thesources, as B is an operators key 70 and a resistance 1, this resistanceserving to prevent complete short circuit of the source B when the keyis is closed. The two sources B and B with the key 73 and the resistancer, serve as transmitting apparatus whereby impulses alternating inpolarity are impressed upon the line. For receiving messages from theother station, there is provided a transformer T whose primary winding Pis connected in the line circuit and whose secondary S is closed throughthe polarized relay R, whose contacts control a local circuit containinga source of current 6 and an electro-magnet m of a sounder, recorder, orany other suitable type of signal translating instrument. In shunt tothe primary winding P is connected a condenser K of suitable capacity.This condenser is found to be desirable, though it may be entirelyomitted. A third winding, the primary P is associated with the magneticcircuit of the transformer T and is, therefore, in inductive relationwith the secondary S. The primary P is connected in circuit with asource of current 13 and the adjustable resistance 1.

While an open magnetic circuit transformer may be employed, I prefer onehaving a closed magnetic circuit, as shown in Fig. 2, where the core Cforms such closed magnetic circuit, the primary P and the secondary Sbeing disposed upon the middle limb of the core, while the primary P maybe disposed as shown, upon one of the outer limbs.

The operation is as follows: The operators at the two stationsmanipulate their keys is in the usual manner to represent dots anddashes, and thereby impress upon the line impulses alternating inpolarity. The line having great capacity or great KR (product ofcapacity and resistance), the impulses received from a distant stationare quite feeble but, by means of the transformer T, the first arrivingincrement of each impulse is transformed and impressed upon thepolarized relay R to actuate the same and thus control the localcircuit, as explained in my co-pending application Serial No. 422,619.But, while these impulses are being received from the distant station,the operator at the home station may transmit a message to the distantstation without interfering with the message coming from that distantstation. To this end, the primary P is employed, the manipulation of loothe key is serving to open and close the circuit through the primary Pand thereby impress impulses upon the secondary S. The source of energyB is so connected with relation to B and the number of turns in theprimary P so adjusted, that the impulses transmitted to line are, so faras the secondary S is concerned, entirely neutralized by the effectproduced by the primary P, so that the home receiving instrument doesnot respond to impulses transmitted to line at the home station. Toadjust this neutralizing effect, the number of turns in the primary Pmay be adjusted, or the source B may be adjusted, or the resistance rmay be adjusted. Therefore, it follows that over a line or cable of thecharacter described two messages may be transmitted simultaneouslyWithout interference with each other. And it is apparent that in thissystem no artificial line or cable is employed.

What I claim is:

1. In duplex telegraphy, the combination With the line, of receivingapparatus comprising a transformer Whose primary is associated With saidline, a receiving instrument controlled by the transformer secondary,and a third winding upon said transformer associated with thetransmitting apparatus for neutralizing in the transformer secondary theeffect of the transmitted impulses.

2. In duplex telegraphy, the combina tion With the line, of transmittingapparatus comprising means for impressing upon said line impulsesalternating in polarity, and receiving apparatus comprising atransformer Whose primary is associated With said line, a signalinginstrument controlled by the transformer secondary, and a third Windingon said transformer and associated With said transmitting apparatus forneutralizing in the transformer secondary the effect of the transmittedimpulses.

3. In duplex telegraphy, the combination With the line, of a receivinginstrument connected in a circuit in inductive relation With said line,transmitting apparatus for impressing upon said line impulses alternatmgin polarity, and an inductive connection between said receivinginstrument and transmitting apparatus for neutralizing in said receivinginstrument the effect of the transmitted impulses.

4. In duplex telegraphy, the combination with the line, of a receivinginstrument, oppositely disposed sources of energy, a circuit in shunt toone of said sources including a key, a circuit including the primary ofa transformer and said hey, said receiving instrument being included ina circuit in inductive relation to said line and in inductive relationto said primary.

5. In duplex telegraphy without an artificial line, the combination witha line or cable having great capacity, of a receiving instrumentconnected in a circuit in induct ive relation with said line or cable,transmitting apparatus for impressing current impulses upon said line orcable, and a winding associated with said transmitting apparatus and ininductive relation with the circuit including said receiving instrumentfor neutralizing in the circuit of said receiving instrument the effectof the transmitted current.

6. In duplex telegraphy, the combination with the line, of a closedmagnetic circuit transformer, the transformer primary connected in saidline, a receiving instrument connected in the transformer secondarycircuit, transmitting apparatus for impressing current impulses uponsaid line, and a winding associated with the magnetic circuit of saidtransformer and controlled by the transmitting apparatus forneutralizing in the transformer secondary the effects of the transmittedimpulses.

In testimony whereof I have hereunto affixed my signature in thepresence of the two subscribing witnesses.

ISIDOR KITSEE.

lVitncsses Amen S. MARsII, ANNA E. Srmnnomc.

